That's funny.........!!!
Had a boss once.......... had a bunch of us testing a condominium complex (open undercabs) by hand and only by hand...............what an idiot.......... I should have died and sued him.
:huh:
Anyone know why voltage 120/240 is referred to as 110/220
- Thread starter ritelec
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That's funny.........!!!
Had a boss once.......... had a bunch of us testing a condominium complex (open undercabs) by hand and only by hand...............what an idiot.......... I should have died and sued him.
:huh:
kwired
Electron manager
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- NE Nebraska
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If it were to change it needed to happen like 50-60 years ago, not going to be easy to do now.
I guess you can do what you want, I find the older I get the less desirable some of those practices you mention become to me - even without pressure from others about how unsafe something is.
How big of a gouge is burned into your screwdriver has more to do with available fault current than voltage level. In dwellings the supply transformer is often smaller which helps to limit the max current, but get into commercial/industrial and the voltage often means very little when it comes to available fault current. Overcurrent device response time also factors in just how much your tool gets burned.
With the infrastructure already in place, I agree. It would be difficult to change now.
wallypiper
Member
- Location
- Atlanta, GA, USA
I was taught that the higher number (480, 240, 120) is the supply voltage and the lower numbers (460, 230, 115) are utilization voltage. Equipment/appliances are designed to run at the utilization voltage allowing voltage drop.
I recently watched a big project grind to a halt for a day and a half while we waited for the POCO to come and adjust their transformer which was supplying 495 volts. That is pretty common early on in a big project as the output voltage from the transformer is expected to drop as the connected loads get energized. But 495 was deemed to high for one of the $$$$ productions machines (nameplated at 460 as it should have been) and there was not much load left to be energized, at least for a few months.
I've been on jobs in Asia where the supply voltage may be called out at 380, 400 or 415 and frequently is actually 419-420 at that early, no loads running yet, stage.
I recently watched a big project grind to a halt for a day and a half while we waited for the POCO to come and adjust their transformer which was supplying 495 volts. That is pretty common early on in a big project as the output voltage from the transformer is expected to drop as the connected loads get energized. But 495 was deemed to high for one of the $$$$ productions machines (nameplated at 460 as it should have been) and there was not much load left to be energized, at least for a few months.
I've been on jobs in Asia where the supply voltage may be called out at 380, 400 or 415 and frequently is actually 419-420 at that early, no loads running yet, stage.
mbrooke
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I wouldn't be working or testing circuits that way regardless of voltage. 120 can still kill. Though uncommon it creates the perception 120 is safe and people become careless to the point it comes back to harm. Voltage is irrelevant in fault carnage, its determined by the trip curves in a breaker combined with the contact separation time as well as the impedance of the circuit. A have cut into a QO breaker at 240 on an AC / 120 on branch circuit more than once and the line men pliers only had a singe. Cut into a FPE things get interesting even if the breaker does trip which usually it does, just a lot latter since FPEs have nearly no functioning magnetic trip.
I could see the sense in moving to a 240V system in homes, but it would be even harder to change to than converting the country to metric (which would actually be pretty easy). It would make trillions of dollars worth of equipment obsolete overnight. It would certainly make 200A services in residential seem very strange. Based on wire gauge, our 15A circuits would become 16A, 3kW circuits (based on international standards) and 20A circuits would become 25A 6kW circuits - as much as many apartments have around Europe...
On the plus side, it would certainly act as a deterrent to working live.
Changing to over to 240 wouldn't require changing the ampacity tables. Only thing we would see are more double pole breakers in the panel and a few less home runs. Of course it would be phased in, homes would at first have both 120 and 240 volt plug, nothing 14/3 in new construction cant handle. New appliances would have the option of being bought as 120 or 240.
All that would need to change in residential would be the breakers and outlets. American homes already have 240 volts, just divided in two for 120. Commercial would be an issue since 415 is far from standard even in the EU sine its acompanied with 50hz rather than 60.
kwired
Electron manager
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- NE Nebraska
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- EC
I wasn't trying to imply that changing premises wiring would be much of a problem, people just have too many appliances that already operate at 120 volts and forcing them to change to an all new system is not going to go over very well with the general public. You did hit on commercial - there is a lot of 120 volt equipment used there as well, along with 480 volt equipment and 277 volt lighting is pretty common also.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Not to write a book on the subject but, back when Edison developed his lamp he determined that it worked most efficiently at 100 volts DC, I guess this was a trade off between longevity of the filament and the voltage drop in the DC circuits.
When Tesla/Westinghouse settled on a voltage and frequency for his Polly-phase alternator (2-phase) at Niagara Falls he based the system voltage and frequency upon being able to power Edison's lamps, the 25 hertz was to keep the lamp from strobing and was based upon being one hertz above the frequency that was used to show motion pictures which was 24 frames a second, because the lamp was rated at 100 volts DC it was determined that a higher voltage was needed to overcome the lower average voltage that AC had without causing the lamp to burn out prematurely from the higher peak to peak voltage, so they settled on 110 volts and multiples of it, at least that is the way I remember it from books on Tesla.
The steel mill where I work was built back in the early 1900's it opened in 1908 and we still have old abandon switch gear labeled 110/220 vac 25 hz 2/ph as well as switch's marked for lighting control labeled 100 VDC.
Also a few years ago I had the pleasure to do some work in an old Chinese Theater that had old Edison control panels all marked 100 VDC all open copper buss with knife switch's and the fuses were nothing but fuse wire wrapped around screws, sometime in the past it was connected to a 110/220 volt 25hz service so all the stage lighting all still worked, the owner said he would never turn the lights up past 25% on the large rheostats so the lamps would not burn out but it still had Edison lamps installed, I just wish I had a camera at the time.
mbrooke
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Most of the world actually has 3 voltages, 220/380 230/400 and 240/415, for various reasons others would know more than me. I do know that great britian was 240 while eastern Europe was 220. The EU decided to merge them toward a unified standard of 230/400Y. But in older installs its any bodies guess
I have to agree. I dont think the public would abhor it once its explained as beneficial, but I can without a doubt guarantee you people will be making adapters, wiring appliances in series and bending prongs to fit
Along with a lot of smoke to celebrate:roll::lol:Nice..............thanks hurk!!
Here, where we have nominally 230V (but really 240V usually) single phase for domestic, one side of it is neutral so we use single pole breakers for protection.
And all light bulbs appliances and anything else rated for 120V.
If it wasn't accomplished at a single stroke for all residences, you'd end up having to have, for example, different bulbs for 120V and 240V available.
Then you have the potential risk of someone sticking in a 120V bulb when it should have been 240V. It isn't insurmountable. You could continue with Edison screw fixtures for 120V but have bayonet cap (BC) for 240V so that it would be impossible to fit the wrong bulb. But you would have to change all the light fixtures in the residence. Again, that can be done but it's just another escalation of the task.
How about light switches? Are they 240V rated? What about dimmers?
Don't misunderstand me. I do think having a single domestic/light commercial voltage could simplify installation and use.
It's the getting there from where you are presently that is probably the show stopper.
mbrooke
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The united Kingdom used to be 240 but because is the regulations I heard its going to 230...
Kind of going backwards in a way. You do have a point regarding the actual switches/dimmers/hardware. We would probably need bayonet sockets or modified GU24 sockets. The incandescent sockets would have to be phased out both because its associated with 120 volts and the fact the shell would be live since our 240 is 2 phases.
But if interested on a side note, if a company was to send an Edison base lamp holder to UL today to be approved as new (edisons were not the norm at all) it would fail nearly all criteria. Edison screw bases are actually considered dangerous since one could easily stick a finger inside or over wattage a fixture, however because they are so common the law makes an exception indefinitely on them. In the future we will probably be seeing GU24s gradually phasing out edison screw shells due to the energy requirements but that is another story.
Anyway, back on topic. The only way I could see a conversion taking place is in steps. Newer homes would get both NEMA 5-15 and 6-15 plugs wired via 14/3 home runs to take care of both. Switches would need to be a heavy duty type along with double volt dimmers. The cost here would be negligible since manufacturers can easily redesign. Older homes would be latter in the step however.
But, in my opinion the biggest set back by far will be DIY. We will be seeing a lot of modifications and internet pages on "how to run 240 volt appliances on 120/120 on 240". First, take a screw driver, then some cord...:happyno:
This hints to the voltages going from 110 to 115 to 120 if OPs interested:
http://www.cooperindustries.com/con...urces/library/201_1phTransformers/R201902.PDF
kwired
Electron manager
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- NE Nebraska
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NEC doesn't prohibit the shell of a lampholder from being connected to an ungrounded conductor, it just requires the shell to be connected to the grounded conductor if the circuit uses a grounded conductor.
There are 230 volt edison based lamps out there - kind of rare but they do exist. There is also edison base HID lamps connected to 208 or 240 volt circuits with no grounded conductor to connect to the shell of the lampholder.
It's been 230V for some time. It was a move designed to harmonise with EU land. UK was, as you rightly say. 415/240. Mutch of EU was 380/220.The united Kingdom used to be 240 but because is the regulations I heard its going to 230...
There was a typical EU fudge. Take the average and make it all that average. At least as a nominal voltage. Oh, and fix the tolerances to suit. In practice, not a lot actually changed.
mbrooke
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It's been 230V for some time. It was a move designed to harmonise with EU land. UK was, as you rightly say. 415/240. Mutch of EU was 380/220.
There was a typical EU fudge. Take the average and make it all that average. At least as a nominal voltage. Oh, and fix the tolerances to suit. In practice, not a lot actually changed.
I think the hold back is utilities. Transformers can last 80 years, and those built to output 240 aren't leaving any time soon. Of course on could argue set the taps lower at the 110kv to 11kv substation transformer, however that isn't always possible. If a distribution feeder already encountering voltage drops at the end that already give say 228 volts at the customer from length or loading doing a 5 or 10% reduction might meet requirements at the beginning and middle of the line but not the end of it. End customers might see 218. Same goes for the secondary 240/415 network if its engineered that way.
If you used just 2-wire 240V, wouldn't you earth (ground) one of the conductors?
You could, but currently in the US 240 is center tapped, rarely is it corner grounded. Grounding one leg would mean everything would have to be changed over to direct 240, you couldn't have dual 120/240 which would allow for a gradual changeover. You could not reuse the old power equipment either. Utility transformers already have the mid point grounded, in order to ground a leg the units would need to be modified or even replaced, which would be cost impractical. Breakers couldn't be re used either since breakers in the US are rated for 120 volts phase to ground, even the double poles since in the US the phase to ground voltage is always 120. 240 phase to ground may allow single pole breakers but they would have a reduced interrupting rating since the voltage they would be interrupting is higher.
3rd having 120 to ground instead of 240 in residential has its perks. In the US DIY electrical work is common. If you own the home and you live in it you can do your own work. Technically you should have it permitted and inspected...but... not everyone does nor do they get caught. 120 volt shocks are many times safer than 240 volt ones. At 240 twice the current passes, which means 4 x the power. At 240 its also easier to sustain an arc if something was shorting to ground. And if a neutral became grounded, it would go unnoticed unless GFI (RCD) protection was used. RCDs are rare in American panels. About the only time you find one are for the bathroom circuits, but about 95% of the time its done through a GFI outlet next to the sink or where ever required. Its rare the wiring in the wall is GFI protected. There is an exception in that some AFCIs have RCD logic in them for 30ma. AFCIs are only required in new construction on some 120 volt circuits here in the states. Other than that GFI/RCD protected wiring is non existent.
Appliance manufacturers would be the ones who would have the easiest time though. Since many of them like Philips already have plants making 2 separate voltage appliance 240 would mean just on production in line. frequency would not be exempt but all switch mode power, heaters/hair dryers/ TVs/ vacuums ect wouldn't care.
Any way my 2 cents
There was a typical EU fudge. Take the average and make it all that average. At least as a nominal voltage. Oh, and fix the tolerances to suit. In practice, not a lot actually changed.
I think the hold back is utilities. Transformers can last 80 years, and those built to output 240 aren't leaving any time soon. Of course on could argue set the taps lower at the 110kv to 11kv substation transformer, however that isn't always possible. If a distribution feeder already encountering voltage drops at the end that already give say 228 volts at the customer from length or loading doing a 5 or 10% reduction might meet requirements at the beginning and middle of the line but not the end of it. End customers might see 218. Same goes for the secondary 240/415 network if its engineered that way.
If you used just 2-wire 240V, wouldn't you earth (ground) one of the conductors?
You could, but currently in the US 240 is center tapped, rarely is it corner grounded. Grounding one leg would mean everything would have to be changed over to direct 240, you couldn't have dual 120/240 which would allow for a gradual changeover. You could not reuse the old power equipment either. Utility transformers already have the mid point grounded, in order to ground a leg the units would need to be modified or even replaced, which would be cost impractical. Breakers couldn't be re used either since breakers in the US are rated for 120 volts phase to ground, even the double poles since in the US the phase to ground voltage is always 120. 240 phase to ground may allow single pole breakers but they would have a reduced interrupting rating since the voltage they would be interrupting is higher.
3rd having 120 to ground instead of 240 in residential has its perks. In the US DIY electrical work is common. If you own the home and you live in it you can do your own work. Technically you should have it permitted and inspected...but... not everyone does nor do they get caught. 120 volt shocks are many times safer than 240 volt ones. At 240 twice the current passes, which means 4 x the power. At 240 its also easier to sustain an arc if something was shorting to ground. And if a neutral became grounded, it would go unnoticed unless GFI (RCD) protection was used. RCDs are rare in American panels. About the only time you find one are for the bathroom circuits, but about 95% of the time its done through a GFI outlet next to the sink or where ever required. Its rare the wiring in the wall is GFI protected. There is an exception in that some AFCIs have RCD logic in them for 30ma. AFCIs are only required in new construction on some 120 volt circuits here in the states. Other than that GFI/RCD protected wiring is non existent.
Appliance manufacturers would be the ones who would have the easiest time though. Since many of them like Philips already have plants making 2 separate voltage appliance 240 would mean just on production in line. frequency would not be exempt but all switch mode power, heaters/hair dryers/ TVs/ vacuums ect wouldn't care.
Any way my 2 cents
I know. With my wife being from GA, I have a foot in both camps....
But what's to stop the 120-0-120 centre tap being dropped and 240 live and neutral being used if you want to go just 240V?
mbrooke
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I know. With my wife being from GA, I have a foot in both camps....
But what's to stop the 120-0-120 centre tap being dropped and 240 live and neutral being used if you want to go just 240V?
Ok Im back:lol:
Once the conversion is finalized you could if we decided to feed resi with 240/415Y, which you be 3 or 4 times more efficient than a center tap. However I would really recommended a device to detect open neutrals since it is a real issue few power experts are willing to address. I know Im a safety freak:ashamed1:
But efficiency aside I think its safer to have 120 to ground instead of 240. Resi would be that in my world while commercial with qualified people would be 240/415Y. J
ust wondering, don't EU job sights require an isolation transformer that's center tapped for 120-0-120 in case someone get a shock?
Wilmon Culley
Member
- Location
- Weirton , WV , USA
120 is line side source 110 is load side utilization
Wilmon Culley
Member
- Location
- Weirton , WV , USA
120 is line side source 110 is load side utilization VD
kwired
Electron manager
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Why you think 240 is more efficient than 120/240? Especially 3 or 4 times more efficient?
Watts is still watts. If the 120 volt loads are relatively balanced you don't really have much for line loss on feeders or service conductors either as the line losses are essentially about the same as they would be if the same load were connected to straight 240 volts. Only the line losses from the imbalance flowing on the neutral is extra inefficiency.
liquidtite
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I thought 110 came bc it's alternating current and you could read 110,115,118 etc
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